1. Field of the Invention
This invention relates generally to the field of paving roads and specifically to reducing fumes from asphalt during paving.
2. Description of the Related Art
Asphalt, comprising tar and an aggregate, such as stone, has long been used as a paving material for roads, parking lots, sidewalks and other surfaces. Hot asphalt is transported to a paving site where it is spread on a graded base surface, such as soil, sand, gravel or old pavement. The asphalt is then leveled or shaped to a desirable configuration in which it cools and hardens to provide a durable paved surface.
In laying asphalt pavement roadways and the like, it is a widespread practice to employ so-called floating screed paving machines. These machines include a tractor-like main frame having an engine for propulsion and for material distributing functions. Typically, there is a material receiving hopper at the front of the paver arranged to receive hot asphalt material from a truck as the paving machine advances along the roadbed. Slat conveyors or the like are provided to convey the material from the hopper, at the front of the machine, toward the floating screed, at the back of the machine. Immediately in front of the screed, there is typically provided a distributing auger, which receives the raw asphalt material from the slat conveyor and conveys it laterally so as to distribute the material along the front edge of the screed. As the machine advances along the prepared roadbed, the raw asphalt material flows under the screed, which levels, smoothes and compacts it to provide a continuous, level pavement mat.
The paving material comprises an aggregate and a bituminous material. The bituminous material is generally asphalt derived from petroleum. The asphalt is composed of hydrocarbons and heterocyclic compounds containing nitrogen, sulfur, and oxygen. Typically these are pre-mixed and transported to the paving site, but they may be mixed on-site or as a part of the paving process. The mixture is sometimes referred to as asphalt or blacktop. A related bitumen, tar, is sometimes used in the same manner as the asphalt or is sprayed onto a surface covered with aggregate. Some of the materials in the asphalt or tar exhale gasses or fumes which are irritating or potentially harmful to persons, plants and animals near the paving operation. In particular, a "screed operator" is typically positioned near the screed and a "paver operator" rides atop the paver as the asphalt is being distributed and leveled. The gasses include undesirable benzine or benzene rings.
It would be desirable to contain the fumes so as to isolate the screed operator and others from the fumes. It would further be desirable to process the fumes so as to remove or reduce the undesirable effects of the components of the fumes before discharging the fumes to the atmosphere.